Sodium chromite has a layer structure, in addition to which sodium chromite has the distinctive property of releasing and absorbing sodium ions. Sodium chromite is therefore used as a positive electrode material in secondary batteries. Moreover, as disclosed in Patent Document 1, sodium chromite is also used as a solid lubricant capable of use in high-temperature liquid sodium and in a high vacuum.
Sodium chromite is produced by, for example, the method described in Non-Patent Document 1; that is, by mixing together a sodium carbonate powder and a chromium oxide powder, then heating the resulting mixture in an inert gas atmosphere.
However, in addition to sodium chromite, the foregoing method also forms by-products such as sodium chromate (Na2CrO4) and CrOOH. Hence, there exists a need for technology that reduces the amount of such by-products.